1. Field of the Invention
The present invention relates generally to optical fiber, and more particularly to coating systems for optical fiber and coated optical fibers.
2. Technical Background
Optical fiber has acquired an increasingly important role in the field of telecommunications, frequently replacing existing copper wires. This trend has had a significant impact in all areas of telecommunications, greatly increasing the amount of data that is transmitted. Further increase in the use of optical fiber is foreseen, especially in metro and fiber-to-the-home applications, as local fiber networks are pushed to deliver an ever-increasing volume of audio, video, and data signals to residential and commercial customers. In addition, use of fiber in home and commercial premise networks for internal data, audio, and video communications has begun, and is expected to increase.
Optical fiber is typically made of glass, and usually has a polymeric primary coating and a polymeric secondary coating. The primary coating (also known as an inner primary coating), is typically applied directly to the glass fiber, and when cured forms a soft, elastic, compliant material encapsulating the glass fiber. The primary coating has a low Young's modulus, and serves as a buffer to cushion and protect the glass fiber during bending, cabling or spooling. The secondary coating (also known as an outer primary coating) is applied over the primary coating, and acts as a tough, protective outer layer that prevents damage to the glass fiber during processing, handling and use.
As the demand for optical fibers has increased, so has the desire to improve the processes used to make them. One common trend in the optical fiber industry has been the desire to draw optical fibers at increased speeds, thereby increasing the throughput of optical fiber manufacturing plants. However, the draw speed can be rate-limited by the step of curing the conventional polymeric coatings used to protect the fiber. One sign that a coating is applied to an optical fiber at a rate exceeding the coating's maximum draw speed is the presence of defects in the cured coating. There remains a need for optical fiber coatings that can be fully cured at higher draw speeds using standard optical fiber coating curing processes.